Ab initio calculation on the low-lying excited states of BCl radical

The internally contracted multi-reference configuration interaction method (MRCI) is used to calculate 22 Lambda-S electronic states of BCl radical at the level of aug-cc-pVQZ basis set, where Davidson modification with the Douglas-Kroll scalar relativistic correction is also taken into account. This is the first time multi-reference configuration calculation on the excited state of BCl radical. Spin-orbit coupling effect is introduced by the state interaction approach with the full Breit-Pauli Hamiltonian operator for the two lowest excited and ground Lambda-S states. The potential energy curves of the Lambda-S and Omega electronic states are depicted according to the avoided crossing rule of the same symmetry. The spectroscopic constants for the bound Lambda-S and Omega states are fitted, which are in good agreement with the corresponding observed values. The calculated excitation energy separation of a(3)Pi(0-)-a(3)Pi(0+) is only 0.22 cm(-1), while the energy intervals of a(3)Pi(0+)-a(3)Pi(1) and a(3)Pi(1)-a(3)Pi(2) are 47.85 cm(-1) and 48.06 cm(-1), respectively. In addition, transition dipole moments (TDMs) followed by Franck-Condon factors and radiative lifetimes for the transitions from a(3)Pi(0+), a(3)Pi(1) and A(1)Pi(1) to the ground state X-1 Sigma(+)(0+) are predicted as well. (C) 2012 Elsevier B.V. All rights reserved.